After booting and the desktop has populated, a bubble pops up saying "your computer might be at risk, anti software might not be installed, click this balloon to fix this problem" and then there's a little blink of the monitor and the screen freezes. I use this machine only for email and keeping my check book, no heavy work, but it's about 6+ years old. I removed the avg free virus software the other day and the spybot free software as well. It has booted sucessfully since then, and was working well last night after several attempts to get it started. Today, complete the startup. My wife accidently tossed the restore disk, she forgot I still had the machine, so any ideas out there? Fortunately I have backed up the important stuff. Thanks and happy new year.

There is a Windows Security Center prompt that comes up where AV software has been uninstalled and the Security Center settings have remained in place to check that you are protected. To be sure it's Windows providing the prompt, you could include a screen shot next time you post.

The screen freezing is worrying. What happens if you start in SAFE mode? Does this still happen?

Can you re-install AVG and see what happens?

If still no good, you'll need to open a post in the Virus/Spyware forum with a HijackThis log (if it lets to make one).